Monitoring and detection systems for spun filaments



R. HORNE July 28, 1964 MONITORING AND DETECTION SYSTEMS FOR SPUN FILAMENTS Filed Oct. 26. 1961 INVBVTOR. RONALD HORNE Wm My ATTORNEY United States Patent 3,142,832 MONITORING AND DETECTION SYSTEMS FOR SPUN FILAMENTS Ronald Horne, Pensacola, Fla., assignor, by mesne assignments, to Monsanto Company, a corporation of Delaware Filed Oct. 26, 1961, Ser. No. 147,837 3 Claims. (Cl. 340-259) This invention relates to monitoring systems and more particularly to circuits for monitoring the denier of spun filaments.

In the manufacture of spun filaments it is of utmost importance that the denier of the filaments be uniform. Variations in denier will considerably lower the quality of the yarn, since these variations will be visible in the fabric made from the yarn. One of the causes of denier variations is fluctuations in the pressure applied to the spinning solution in the spinning head. A drop in pressure behind the spinnerette will result in a reduction in the diameter of the spun filaments. This is commonly referred to as spinnerette starvation.

In one type of melt spinning operation the filaments leave the spinnerette and pass downward through a chimney to rolls which advance the filaments to a takeup device. A stream of air is directed transversely across the chimney to cool and solidify the freshly spun filaments. In conventional spinning operations samples of the filaments are taken and measured for denier. The disadvantage of this method is that many yards of undersize yarn may be produced before the defect is detected. Of course, all of this yarn will be of very poor quality and may even be unusable. The embodiment of this invention disclosed herein monitors the denier of the filaments passing through the chimney and gives an alarm at once in the event of spinnerette starvation. Thus, a denier variation is detected and can be corrected at once.

One of the objects of this invention is to provide a novel and improved monitoring system.

Another object of this invention is to provide a system for monitoring spun filaments to detect denier variations therein.

A further object of this invention is to provide a system for automatically and continuously monitoring the denier of spun filaments at the spinnerette.

Still another object of this invention is to provide a circuit which operates an alarm or control in response to a decrease in the denier of a spun yarn.

A still further object of this invention is to provide a system utilizing a light source and a light-responsive resistor for detecting spinnerette starvation.

Yet another object of thisinvention is to provide a system utilizing a light source and a light-responsive resistor for detecting spinnerette starvation and having a time delay for compensating for deterioration of the light source and drift of the light-responsive resistor.

One embodiment of the present invention contemplates a monitoring system wherein a light beam is projected across a spinning chimney onto a light-responsive resistor which is connected in a monitoring circuit. If the proper pressure is maintained behind the spinnerette the filaments will be of proper size and the air stream will sweep these filaments toward one side of the chimney to keep them out of the light beam. If, however, the pressure behind the spinnerette drops, the diameter of the filaments will decrease and one or more of the filaments will move into the light beam. This causes an increase in the resistance of the light-responsive resistor to trigger the monitoring circuit which operates an alarm or control. A capacitor connected in series with a resistor across the light-responsive resistor serves as a time delay to prevent triggering of the monitoring circuit in the event 3,142,832 Patented July 28, 1964 ice of incipient deterioration of the light source or drift of the light-responsive resistor.

Other objects and advantages of the invention will become apparent when the following detailed description is read in conjunction with the appended drawing, in which the single figure illustrates one embodiment of the invention and shows a schematic diagram of the circuit and a fragment of the spinning chimney.

Referring now in detail to the drawing, a spinning head 11 mounted on a chimney 12 is shown forming filaments 14. The filaments 14 are formed when a molten spinning solution is forced under pressure through holes in a spinnerette (not shown) held within the spinning head. A stream of air from a nozzle or manifold 17 connected to an air source 18 is directed laterally across the spinning chimney to cool and completely solidify the freshly spun filaments 14. These cooled filaments then pass between guide pins 19 and are taken up at a constant speed by well known equipment (not shown).

If the pressure in the spinning head is at the proper value the spinning solution will be forced through the spinnerette holes at a high enough speed to provide a slight amount of slack in the filaments 14. This slack will allow the air stream to deflect the filaments from a straight path, as shown in the drawing. If, however, the spinning head pressure drops, the solution will pass through the spinnerette holes at a slower rate. This will cause the takeup mechanism (not shown) to pull the filaments back onto a straight path and into alignment with a pair of slits 22 and 23 in the spinning chimney. Because of the constant speed of the takeup mechanism, the denier of the filaments 14 will be decreased. Thus, a decrease in denier is accompanied by a movement of the filaments from the deflected path to a straight path in alignment with the slits 22 and 23.

A light source 26 positioned adjacent to the slit 22 directs a light beam laterally across the chimney 12, through the slit 23 and onto a light-sensitive cadmiumsulphide cell or resistor 27 of a well known type which varies in resistance in response to variations in the intensity of the light beam. As the intensity of the light beam increases, the resistance of the resistor 27 decreases.

The cadmium-sulphide resistor 27 is connected across a DC. power supply 28 in series with a variable resistor 29. The resistor 29 is adjusted so that, under normal operating conditions, the voltage across the light-respon sive resistor 27 is very low. A capacitor 32 is connected in series with a variable resistor 33 across the light-responsive resistor 27 to provide a triggering voltage in the event of a decrease in filament denier. This triggering or gate voltage appears across the resistor 33, a junction 34 of the resistor 33 and the capacitor 32 being connected as shown to the base of a silicon controlled rectifier 36.

The silicon controlled rectifier 36 is connected in series with a reset switch 37 and a neon lamp 38 between a tap 39 of a potentiometer 40 and one end of the potentiometer. The potentiometer 40 is connected across a DC. power supply 41.

In operation of the present embodiment, the filaments normally follow the path shown in the drawing and the intense light beam holds the resistance of the cadmiumsulphide cell 27 to a low value. Under these conditions the voltage across the resistor 33 is too low to trigger the rectifier 36, so that the neon lamp 38 is not lit.

In the event of a pressure drop in the spinning head, the filaments 14 will assume a straight path and will partially block off light from the source 26. This greatly increases the resistance of the light-responsive resistor 27. When the resistance of the resistor 27 increases, the capacitor 32 will begin to charge to a higher voltage than under normal circumstances. Because the capacitor must charge through the resistor 33, the triggering voltage does not appear at once across the resistor 33. Instead, the voltage at the junction 34 builds up over a short time period until it is sufiiciently high to trigger the rectifier 36, whereupon the neon lamp is illuminated to let the operator know that the filaments are not of proper denier. The operator can then take whatever steps that are necessary to correct the situation.

The silicon controlled rectifier 36, being similar in operation to a thyratron tube continues to conduct until the operator momentarily opens the reset switch 37. If the defect has been corrected, the neon lamp 38 will not be again lit until, for some reason, the filament denier drops. A capacitor 42 connected across the rectifier 36 as shown assures a sharp cutoff of the rectifier when the switch 37 is opened.

The capacitor 32 provides a time delay to prevent triggering of the rectifier 36 in case the light intensity fluctuates or the resistance of the resistor 27 fluctuates. This is because the voltage across the resistor 33 does not increase instantaneously with the voltage across the lightresponsive resistor 27, but builds up rather slowly as the capacitor 32 charges. Thus, fluctuations of a transient nature in the voltage drop across the resistor 27 do not trigger the silicon controlled rectifier. This prevents false alarms.

This system provides an immediate inspection of spun filaments, so that necessary corrections can be made at once rather than after a large amount of off-denier yarn has been spun. Also, this system provides an automatic inspection of all of the yarn rather than just short portions as is the case with conventional inspection.

It is to be understood that the embodiment disclosed herein is merely illustrative and that this embodiment may be modified or altered and that numerous other embodiments may be contemplated which will fall within the spirit and scope of the invention.

What is claimed is:

1. A system for detecting a decrease in denier of spun filaments, comprising a base, means on the base for directing a stream of fluid against a plurality of spun fila ments to urge said filaments out of a straight path, a light-responsive resistor positioned at one side of said straight path, a light source positioned on the other side of said path for directing a beam of light through said path to the light-responsive resistor, a resistance connected in parallel with the light-responsive resistor, a power supply connected across the resistance and the light-responsive resistor, a junction, a capacitor connected between the junction and one side of said resistor, said resistance being connected between the junction and the other side of the light-responsive resistor, a silicon controlled rectifier having its gate connected to said junction, and means connected to the silicon controlled rectifier for indicating an out-of-limits condition.

2. A system for detecting a strand, comprising a base,

means on the base for directing a stream of gas against the strand to urge said strand out of a straight path, a light source positioned on one side of the path to direct a beam of light through said straight path, a light-responsive resistor positioned on the other side of said path to receive light from said source, a first resistor connected to the light-responsive resistor, a power supply connected across said first resistor and said light-responsive resistor, a first capacitor connected to one side of the light-responsive resistor, a variable resistor connected between the first capacitor and the other side of the light-responsive resistor, a silicon controlled rectifier having its gate connected to the junction of the first capacitor and the variable resistor, a switch, a neon lamp connected in series with the switch to the silicon controlled rectifier to form an indicating circuit, means for applying voltage to the indicating circuit, and a second capacitor connected across the cathode and anode the silicon controlled rectifier.

3. A device for detecting a decrease in denier of freshly spun filaments, comprising a base, a chimney mounted on the base for passage of said filaments therethrough, means connected to the chimney for directing a stream of gas against the filaments to sweep said filaments from a straight path into a curved path, said chimney having a pair of slits on opposite sides thereof, said slits being in alignment with the straight path but out of alignment with said curved path, a light source positioned adjacent to one of the slits for directing a beam of light through both slits, a light-responsive resistor positioned adjacent to the other slit for receiving said beam of light, a power supply connected across the light-responsive resistor, a capacitor, a resistor, said capacitor and resistor being connected in series with each other and in parallel with the light-responsive resistor, a silicon controlled rectifier having the gate thereof connected to the junction of the capacitor and the resistor and the cathode thereof connected to the other side of said resistor, an indicating circuit connected across the cathode and anode of the silicon controlled rectifier, and means connected to the indicating circuit for applying power thereto.

References Cited in the file of this patent UNITED STATES PATENTS 2,233,483 Metcalf Mar. 4, 1941 2,295,366 Stout Sept. 8, 1942 2,432,084 Blair Dec. 9, 1947 2,783,450 Jackson Feb. 26, 1957 2,907,890 ReXon Oct. 6, 1959 2,971,134 Cochrell Feb. 7, 1961 3,026,498 Galliers Mar. 20, 1962 3,044,345 Schottler July 17, 1962 FOREIGN PATENTS 692,726 Germany June 26, 1940 917,296 Germany Aug. 30, 1954 

1. A SYSTEM FOR DETECTING A DECREASE IN DENIER OF SPUN FILAMENTS, COMPRISING A BASE MEANS ON THE BASE FOR DIRECTING A STREAM OF FLUID AGAINST A PLURALITY OF SPUN FILAMENTS TO URGE SAID FILAMENTS OUT OF A STRAIGHT PATH, A LIGHT-RESPONSIVE RESISTOR POSITIONED AT ONE SIDE OF SAID STRAIGHT PATH, A LIGHT SOURCE POSITIONED ON THE OTHER SIDE OF SAID PATH FOR DIRECTING A BEAM OF LIGHT THROUGH SAID PATH TO THE LIGHT-RESPONSIVE RESISTOR, A RESISTANCE CONNECTED IN PARALLEL WITH THE LIGHT-RESPONSIVE RESISTOR, A POWER SUPPLY CONNECTED ACROSS THE RESISTANCE AND THE LIGHT-RESPONSIVE RESISTOR, A JUNCTION, A CAPACITOR CONNECTED BETWEEN THE JUNCTION AND ONE SIDE OF SAID RESISTOR, SAID RESISTANCE BEING CONNECTED BETWEEN THE JUNCTION AND THE OTHER SIDE OF THE LIGHT-RESPONSIVE RESISTOR, A SILICON CONTROLLED RECTIFIER HAIVNG ITS GATE CONNECTED TO SAID JUNCTION, AND MEANS CONNECTED TO THE SILICON CONTROLLED RECTIFER FOR INDICATING AS OUT-OF-LIMITS CONDITION. 